Deck Guide: Legacy Mystic Forge Combo

With the printings of Karn, the Great Creator and Mystic Forge, artifact-based combo decks have seen some on-and-off success over the past two years. There aren’t that many archetypes that can fully take advantage of these two spells, but in the right shell, it can lead to a potent engine.

Legacy stalwart Casey Lancaster shared some impressive testing results with a clean, effective deck list on Twitter and players have started to pick up the archetype quite a bit. Recently, Magic Online player Killersuv came in sixth in the Legacy Showcase Challenge this past weekend with a similar list, so it seemed like a good time to talk about the deck.

Let’s start by taking a look at how this deck works.



Legacy Mystic Forge Combo by Killersuv



Header - Core Game Plan

No matter how you look at it, the plan of this deck is to generate a ridiculous amount of mana and then cast Walking Ballista to win the game. Mystic Forge allows you to churn through your deck at lightning speed, Karn provides additional access to most combo pieces, as well as access to a variety of prison-esque cards and the combo of Mesmeric Orb and Basalt Monolith will let you cast Echo of Eons an incredible amount of times (provided that you have the blue mana).

All three of these plans are executed with a similar set of cards, so let’s walk through the individual choices and see how they fit the plan.


Karn, the Great CreatorMystic Forge


I’m lumping these together as the payoffs. If you can get either one of these to stick around in play, you’ll likely win the game in short order. Karn provides access to a lot of prison tools in the sideboard while also providing access to additional combo pieces. Mystic Forge gives this deck a ridiculous amount of churn, as more than two-thirds of the deck can be cast off of it. You’ll generate a massive advantage in most games that you resolve a Mystic Forge and it’s certainly the most potent engine in the deck.


Echo of EonsLion's Eye Diamond


Echo is a really powerful card engine for a deck like this. Between multiple mana engines and explosive payoffs, drawing seven cards will often provide this deck more than enough resources to put together a combo finish. Lion’s Eye Diamond facilitates the Echo starts, which adds another layer to the deck that’s tough to continuously interact with. Even if they can stop a combo piece or two, following up with a Lion’s Eye Diamond to discard your hand and cast Echo will keep the ball rolling.


Mesmeric OrbBasalt Monolith


This is a two-card combo that allows you to mill as many cards from your deck as you want. Once you assemble this, you’ll find all the copies of Echo of Eons that you might need and you can just keep churning through your deck. Eventually, you’re pretty likely to find a copy of any piece you’re missing and have certainly taken a lot of game actions in the process. Basalt Monolith has some additional utility as a potent mana rock when combined with untap effects


Grim MonolithManifold Key (Timeshifted)Voltaic Key


This is the mana engine that lets this deck go way over the top. Grim Monolith is a great card as it is, but when you combine it with a Key, you can make some absurd amounts of mana. Basalt Monolith can fit into this section as well, which actually demonstrates a point as to why this deck is effective. Its cards don’t just function on a single axis. A lot of the cards have additional synergies with other elements of the deck, which greatly increases the resilience that this deck has. It’s far more difficult to break up a single element of the deck when cards like Basalt Monolith are both a mana engine and a card engine, depending on the context. 


Lotus PetalMox Opal


These are additional pieces of fast mana that let this deck accelerate out combo pieces as fast as possible. They’re particularly effective when Mystic Forge is online in letting you keep moving through your deck and generate mana along the way.


Walking Ballista


A main deck copy of the combo cards does two things. The first is that it increases the chances that you’ll find it, while reducing the reliance on Karn, the Great Creator. The second is that it insulates you from Surgical Extraction in the post-board games. Surgical Extraction on your Karns would otherwise be lights out if you weren’t prepared for it, so having a copy of Ballista floating around in the deck means you can actually win in those circumstances.


Defense Grid


Defense Grid is a really effective card against decks that rely on countermagic. Oftentimes they have to counter it, which will open the door for your payoffs to resolve. It’s one of the best cards to draw against blue decks and should be prioritized rather highly if you know the matchup.


Ancient TombCity of TraitorsCrystal VeinInventors' Fair


This deck wants to accelerate as much as possible, so it plays the full suite of 12 Sol lands. Crystal Vein doesn’t see a lot of play in Legacy these days, as not too many decks are willing to throw away lands for a quick burst of mana. It’s exactly what this deck is looking to do though, so it’s a solid inclusion here. On the other hand, Inventors’ Fair is a nod towards resilience, as it provides extra copies of whatever artifact you’re missing to go off. The life gain isn’t irrelevant either, and it can help buffer your life total against an aggressive start.


Header - The Sideboard

Walking BallistaLion's Eye DiamondMesmeric Orb


These are extra copies of main deck cards that help in very specific situations when you have Karn in play. 


Aetherflux Reservoir


This is not a common card to play in Legacy, but it’s pretty cool here. It’s an additional win condition that also might just be a life gain engine if you just need to make sure you don’t die. 


Ensnaring Bridge


One of the best prison pieces in Legacy, this will just win the game straight-up against a deck that needs to attack to win but doesn’t have an answer to artifacts (looking at you, Delver).


Liquimetal CoatingMycosynth Lattice


These are go-tos in most Karn decks. Mycosynth Lattice will just straight-up lock your opponent out of the game if you can resolve it with Karn in play. Liquimetal Coating will make their lives pretty difficult, as it can just blow up lands every turn or turn off planeswalkers. 


Skysovereign, Consul Flagship


This is an answer to smaller creatures and planeswalkers that can also apply some real pressure. There aren’t that many ways to crew it, but using Karn’s +1 to turn Basalt Monolith into a creature is a pretty straightforward way to accomplish that.


Tormod's Crypt


Decks like Reanimator are always going to be difficult for a deck like this, so Tormod’s Crypt really comes in handy there.


Karn, Scion of Urza


This Karn is anti-Null Rod technology. While it still might be a bit difficult to get the mana to cast it, this Karn can easily dominate a game once you do.


Header - Tips and Tricks

  • Karn can tutor artifacts from exile, so if they Force of Negation your Mystic Forge, don’t forget that Karn can go search that up.
  • The Keys can untap Mystic Forge to help you keep going off.
  • Manifold Key can make creatures unblockable, so if you need to get in some damage, you can Karn +1 on an artifact and use Key to push through a blocker.


Header - Sideboard Guide

Temur Delver

Temur Delver

Out: 2 Mesmeric Orb, 2 Basalt Monolith

In: 4 Karn, Scion of Urza


I could see sideboard a lot of different ways here, but I like trimming on the self-mill combo here. They will likely have Null Rod, so that combo doesn’t work with Null Rod in play. In addition, casting Echo might be necessary against them, but it can be risky as they have plenty of Force effects to interact with you.





Out: 4 Defense Grid

In: 3 Tormod’s Crypt, 1 Lion’s Eye Diamond


Speed is the name of the game here. You could just leave a Tormod’s Crypt in the board to get with Karn, but honestly that’s too slow against most builds of Reanimator. I like bringing in the Diamond to promote fast Echo hands and try to make sure you can go off as quickly as possible and ensure you can find a Tormod’s Crypt.



Death and Taxes

Death and Taxes

Out: 4 Defense Grid

In: 4 Karn, Scion of Urza


Defense Grid has almost no text in this matchup and while Karn is a bit slow, he can have a lot of board impact. For the most part, the primary game plan should be good enough against them, but watch out for Skyclave Apparition or Sanctum Prelate stopping you from comboing.

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